Power tool blade type detection and automatic speed adjustment

ABSTRACT

Systems and methods are provided for an electric tool (e.g., a power tool) that includes an output driver for receiving an accessory, and an accessory-type detector. A motor of the electric tool is coupled to the output driver for driving the accessory. The power tool also includes an operation trigger for activating the motor and a motor controller. The motor controller includes an electronic processor that is coupled to the accessory-type detector, the motor, the operation trigger, and a memory. The memory stores instructions that when executed by the electronic processor cause the motor controller to detect a characteristic of the accessory from output of the accessory-type detector. The motor controller determines an operational characteristic for the accessory based on the detected characteristic, and controls operation of the motor to drive the accessory according to the operational characteristic when the operation trigger is activated.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/656,448, filed on Apr. 12, 2018, which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

Embodiments described herein relate to power tools. More specifically,embodiments described herein relate to automatic control of power toolsbased on detection of power tool accessory type or presence by anaccessory-type detector.

SUMMARY

A power tool generally utilizes an accessory, such as, a blade, agrinding disk, a drill bit, and the like for performing a particulartype of operation. Some power tools are configured to interchangedifferent accessories. Different power tool accessories may havedifferent characteristics, for example, they may be made of differentmaterials, have different dimensions, or they may be designed to performdifferent tasks. The characteristics of a particular accessory, or typeof accessory, may affect the performance of a power tool or may imposeconstraints on operation of the power tool. For example, differentaccessory types may be configured to work at different rotational speedsor applied torque.

In some embodiments, a method for controlling operation of a power toolincludes receiving an accessory by an output driver of the power tool.The output driver is coupled to a motor of the power tool and theaccessory is driven by the motor. A characteristic of the accessory isdetected by a motor controller that is coupled to an accessory-typedetector of the power tool. The motor controller includes an electronicprocessor and a memory. The motor controller determines an operationalcharacteristic for the accessory based on the detected characteristic ofthe accessory. When an operation trigger of the power tool is activated,the motor controller controls operation of the motor that drives theaccessory according to the operational characteristic.

In some embodiments, a power tool includes an output driver forreceiving an accessory and an accessory-type detector. A motor of thepower tool is coupled to the output driver for driving the accessory.The power tool also includes an operation trigger for activating themotor and a motor controller. The motor controller includes anelectronic processor that is coupled to the accessory-type detector, themotor, the operation trigger, and a memory. The memory storesinstructions that when executed by the electronic processor, cause themotor controller to detect a characteristic of the accessory from outputof the accessory-type detector. The motor controller determines anoperational characteristic for the accessory based on the detectedcharacteristic of the accessory, and controls operation of the motor todrive the accessory according to the operational characteristic when theoperation trigger is activated.

In some embodiments, an electric tool includes an output driver forreceiving an accessory and an accessory-type detector. A motor of theelectric tool is coupled to the output driver for driving the accessory.The electric tool also includes an operation trigger for activating themotor and a motor controller. The motor controller includes anelectronic processor that is coupled to the accessory-type detector, themotor, the operation trigger, and a memory. The memory storesinstructions that when executed by the electronic processor, cause themotor controller to detect a characteristic of the accessory from outputof the accessory-type detector. The motor controller determines anoperational characteristic for the accessory based on the detectedcharacteristic of the accessory, and controls operation of the motor todrive the accessory according to the operational characteristic when theoperation trigger is activated.

In some embodiments, the accessory-type detector is coupled to a housingof the electric tool or the power tool.

In some embodiments, the accessory is a saw and the accessorycharacteristic comprises a material of which the saw is made.

In some embodiments, the operational characteristic comprises a speedfor rotating the motor that drives the output driver and the accessory.

In some embodiments, the characteristic of the accessory comprises aphysical characteristic of the accessory or a modification made to theaccessory.

In some embodiments, the motor controller disables activation of themotor when the accessory-type detector detects that an accessory is notreceived by the output driver.

In some embodiments, the motor controller may enable activation of themotor when the accessory-type detector detects that an accessory isreceived by the output driver.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of an electric tool with an accessory andan accessory-type detector.

FIG. 2 is a block diagram of the exemplary electric tool with theaccessory-type detector of FIG. 1.

FIG. 3 illustrates a method for controlling an electric tool based on atype of accessory attached to the tool.

FIG. 4 illustrates an example of a pipe threader tool with a pipematerial-type detector.

DETAILED DESCRIPTION

One or more embodiments are described and illustrated in the followingdescription and accompanying drawings. These embodiments are not limitedto the specific details provided herein and may be modified in variousways. Furthermore, other embodiments may exist that are not describedherein. Also, the functionality described herein as being performed byone component may be performed by multiple components in a distributedmanner. Likewise, functionality performed by multiple components may beconsolidated and performed by a single component. Similarly, a componentdescribed as performing particular functionality may also performadditional functionality not described herein. For example, a device orstructure that is “configured” in a certain way is configured in atleast that way, but may also be configured in ways that are not listed.Furthermore, some embodiments described herein may include one or moreelectronic processors configured to perform the described functionalityby executing instructions stored in non-transitory, computer-readablemedium. Similarly, embodiments described herein may be implemented asnon-transitory, computer-readable medium storing instructions executableby one or more electronic processors to perform the describedfunctionality. As used in the present application, “non-transitorycomputer-readable medium” comprises all computer-readable media.Accordingly, non-transitory computer-readable medium may include, forexample, a hard disk, a CD-ROM, an optical storage device, a magneticstorage device, a ROM (Read Only Memory), a RAM (Random Access Memory),register memory, a processor cache, or any combination thereof.

In addition, the phraseology and terminology used herein is for thepurpose of description and should not be regarded as limiting. Forexample, the use of “including,” “containing,” “comprising,” “having,”and variations thereof herein is meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Theterms “connected” and “coupled” are used broadly and encompass bothdirect and indirect connecting and coupling. Further, “connected” and“coupled” are not restricted to physical or mechanical connections orcouplings and can include electrical connections or couplings, whetherdirect or indirect. In addition, electronic communications andnotifications may be performed using wired connections, wirelessconnections, or a combination thereof and may be transmitted directly orthrough one or more intermediary devices over various types of networks,communication channels, and connections. Moreover, relational terms suchas first and second, top and bottom, and the like may be used hereinsolely to distinguish one entity or action from another entity or actionwithout necessarily requiring or implying any actual such relationshipor order between such entities or actions.

Some electric tools are configured to receive multiple different typesof accessories, for example, saw blades (e.g., reciprocating orcircular), grinding disks, drill bits, driver bits, and variationsthereof made of different materials, sizes, and shapes. However,different accessories may work more efficiently, more accurately, withless wear, or a combination thereof, when utilized with differentoperational characteristics, for example, different linear or rotationalspeeds, acceleration patterns, or directions. In some embodimentsdescribed herein, methods and systems provide a tool component thatsenses what type of accessory is attached to the tool. The tool isconfigured to automatically operate at the appropriate speed,acceleration, or other operating characteristic based on the detectedtype of attached accessory. For example, when a user turns the tool on,the tool may operate at a speed or acceleration appropriate for theattached type of accessory. In one example comprising a chop saw, ablade type may be detected and a speed setting may be automaticallyapplied for driving the saw based on the blade type. When the blade isreplaced with a second type of blade (or a grinder, for example) thesecond blade type is detected and the speed setting is automaticallychanged to a second speed according to the second type of blade.

FIG. 1 illustrates an example of an electric tool 100 with an accessoryand an accessory-type detector. In this example, the electric tool 100is a chop saw and may be referred to as the chop saw 100. The electrictool 100 includes a tool housing 115, a blade guard 120, a powerinterface 125, an accessory 135, a tool activation trigger 140, and anaccessory-type detector 145. The accessory 135 in this example is a sawblade and may be referred to as the blade 135. The housing 115 includesa motor housing 146, a handle 147, a base 148, and a hinge 149 pivotablycoupling the motor housing 146 to the base 148. The electric tool 100may also be referred to as a power tool 100.

Although, the exemplary electric tool 100 is shown as a chop saw, theelectric tool 100 may be any electric tool (or power tool) that drivesan output driver. Such electric tools include, for example, drills,circular saws, jig saws, band saws, table saws, miter saws,reciprocating saws, angle grinders, straight grinders, hammers,multi-tools, impact wrenches, rotary hammers, drill-drivers, hammerdrill-drivers, impact drivers, angle drills, belt sanders, orbitalsanders, planers, pipe cutters, grease guns, vacuum cleaners, fluid flowcontrol devices, outdoor power equipment (such as blowers, chain saws,edgers, hedge trimmers, lawn mowers, or trimmers), and the like. Thevacuum cleaners can include wet/dry vacuums, dust removal vacuums thatmay be connectable to power tools (e.g., saws or sanders), stickvacuums, hand vacuums, upright vacuums, carpet cleaners, hard surfacecleaners, canister vacuums, broom vacuums, and the like. The fluid flowcontrol devices can include motorized water pumps, electronicallycontrollable water flow valves, and the like. The electric tool 100 mayalso include other types of appliances, machines, or devices thatreceive and drive an accessory to perform an operation.

In some embodiments, the housing 115 (in particular, the motor housing146), supports a motor (see FIG. 2) that drives the accessory 135. Forexample, the motor may drive rotation of the blade 135. The housing 115may also support a motor controller and other components that enableoperation of the electric tool 100 (see FIG. 2). The blade guard 120 ismechanically coupled to the housing 115 and is disposed around and/orbeside the blade 135. The blade guard 135 serves as a safety device tocover portions of the blade 135. During operation, the trigger 140 ispulled to activate the chop saw 100 and rotate the blade 135, and thehandle is pulled downward by the operator bringing the blade 135 towardthe base 148 to cut a workpiece (not shown) that is received by andsupported on the base 148. The hinge 149 may be spring-biased such thatthe motor housing 146 returns to an upright position as illustrated inFIG. 1 when the operator releases the handle 147.

The accessory 135 includes a detectable characteristic. Thecharacteristic may be a physical characteristic of the accessory 135 orthe accessory 135 may be modified with a characteristic that identifiesthe accessory type. The accessory-type indicator, as a characteristic ofthe accessory 135, may include an identifying mark or an attached tagthat may be sensed, read, or optically captured by the accessory-typedetector 145. Detectable physical characteristics may include, forexample, a type of material that the accessory is made of, a texture,shape, or size of the accessory 135 or a portion of the accessory 135.For example, a metal accessory versus a non-metal accessory are twotypes of materials that may be detected.

In some embodiments, the power interface 125 is configured to receive aremovable and rechargeable power tool battery pack (not shown) that maybe operable with a suite of two or more of power tools, fluid flowcontrol devices, test and measurement devices, work site radios, andwork lights. The power tool battery pack includes a housing within whichare one or more battery cells, which may be lithium ion (“Li-ion”)cells, Nickel-Cadium (“Ni-Cad”) cells, or cells of another chemicaltype. The cells, collectively, may provide nominal voltages of differentvalues, depending on the pack. For example, the power tool battery packmay have a nominal output voltage of 4V, 12V, 18V, 28V, 36V, 40V, avoltage between levels, or other levels. In some embodiments, the powerinterface 125 is an alternating current (AC) power interface that isconfigured to be connected to a standard AC outlet that is furthercoupled to an AC power grid or AC generator. For instance, the AC sourcemay include an approximately 120 V, 60 Hz power signal or anapproximately 240 V, 50 Hz power signal.

The tool activation trigger 140 is coupled to the electronic processorand supported by the housing 115 and may initiate activation of theelectric tool 100 when actuated or depressed by a user.

The accessory-type detector 145 may be mounted on the blade guard 120(e.g., on the outside or on the inside of the blade guard 120), the toolhousing 115, or on any other structure of the electric tool 100 suchthat the accessory-type detector 145 can detect which type of accessory135 is attached to the power tool 100. For example, in some embodiments,the accessory-type detector has a first sensing side and a secondmounting side opposite the first sensing side. The mounting side may besecured to the inside of the blade guard 120 (e.g., via fasteners,adhesive, welding, and the like), while the sensing side includes asensor with a sensing face directed toward a side face 135 a of theblade 135. The accessory-type detector 145 is configured to detect oneor more characteristics of the accessory 135. In some embodiments, theaccessory-type detector 145 includes an inductive sensor that detectsand provides an indication of whether the accessory 135 is metal ornon-metal. In some embodiments, the accessory-type detector 145 includesan optical sensor that detects and provides an indication of acharacteristic such as the type, size, shape, texture, or material ofthe accessory 135. Other suitable types of sensors may be used as theaccessory-type detector 145, for example, radio frequency identification(RFID), sound, light, tactile or heat sensors. In some embodiments, theaccessory-type detector 145 detects and provides an indication ofwhether or not the accessory 135 is received in place, such as attachedto the electric tool 100. The controller may prevent activation of atool component when the tool activation trigger is pulled and theaccessory 135 is missing or placed incorrectly. Moreover, in someembodiments, the accessory 135 may comprise an identifying mark or a tagthat may be sensed or read by the accessory-type detector 145, and mayindicate which type of accessory 135 is attached to the electric tool100. The mark or tag may include, among other things, one or more of anRF or RFID emitter, an optically detectable feature such as a type ofbar code, a color, a light emitter, and an acoustically detectablefeature or sound emitter.

FIG. 2 is a block diagram of the exemplary electric tool 100 with theaccessory-type detector 145 of FIG. 1. A system 200 of the electric tool100 includes, among other things, the power interface 125, theaccessory-type detector 145, field effect transistors (FETs) 205, amotor 210, an output driver 212, Hall sensors 215, a motor controller220, user input 225, and other components 230 (battery pack fuel gauge,work lights (LEDs), current/voltage sensors, etc.). The motor controller220 may also be referred to as an electronic motor controller or a motormicrocontroller and includes, among other things, an electronicprocessor and a memory. In some embodiments, the memory storesinstructions that are executed by the electronic processor to implementthe functionality of the motor controller 220 described herein.

The output driver 212 is configured to receive an electric toolaccessory 135, for example, a blade or drill. The output driver 212 is,for example, an arbor for receiving a saw blade or a chuck for receivinga drill bit. The accessory-type detector 145 detects characteristics ofthe accessory 135 and communicates data indicating the accessorycharacteristics to the motor controller 220. The Hall sensors 215provide motor information feedback, such as motor rotational positioninformation, which can be used by the motor controller 220 to determinemotor position, velocity, and/or acceleration. The motor controller 220receives user controls from user input 225, such as by depressing thetrigger 140 or shifting a forward/reverse selector of the electric tool100. In response to the accessory characteristic, the motor informationfeedback, and/or user controls, the motor controller 220 transmitscontrol signals to accurately control the FETs 205 to drive the motor210. By selectively enabling and disabling the FETs 205, power from thepower interface 125 is selectively applied to stator windings of themotor 210 to cause rotation of a rotor of the motor 210. The rotatingrotor of the motor 210 drives the output driver 212 and the accessory135 at an appropriate operational characteristic, such as a specifiedspeed, acceleration, and/or direction, according to the accessorycharacteristic. Although not shown, the motor controller 220 and othercomponents of the electric tool 100 are electrically coupled to andreceive power from the power interface 125. The FETs 205 may also bereferred to as power switching elements. The FETs 205, motor 210, Hallsensors 215, motor controller 220, and output driver 212 may be referredto as electromechanical components 235 of the electric tool 100.

As noted above, the accessory-type detector 145 detects one or moreaccessory characteristics of the accessory 135 on the output driver 212and outputs data to the motor controller 220 indicative of the detectedone or more accessory characteristics. Further, in some embodiments, theaccessory-type detector 145 is configured to output an indication to themotor controller 220 of whether an accessory is coupled to the outputdriver 212. In some embodiments, the accessory-type detector 145 is oneor more of an inductive sensor, an optical sensor, a radio frequencyidentification (RFID) sensor, sound sensor (microphone), a light sensor,a tactile sensor, and a heat sensor.

Although described with respect to the example of the chop saw 100 ofFIG. 1, the block diagram 200 generally applies to other embodiments ofthe electric tool 100. For example, the output driver 212 in the case ofa power drill-driver is a chuck; the output driver 212 in the case of avacuum is an impeller providing suction force; and the output driver 212in the case of a water pump is a pumping mechanism. Further, in someembodiments of the electric tool 100, a brushed motor is provided as themotor 210 to drive the output driver 212.

FIG. 3 illustrates a method 300 for controlling an electric tool basedon a type of accessory attached to the tool. In some embodiments, themethod 300 is implemented with one of the embodiments of the electrictool 100 of FIG. 1 and, accordingly, the method 300 will be describedwith respect to the system 100. However, in some embodiments, the method300 is implemented with other systems or other types of electric toolsas described above.

In block 305, the power tool 100 receives the accessory 135 at theoutput driver 212. As part of receiving the accessory 135, in someembodiments, the output driver 212 is tightened, clamped, or otherwisemanipulated (e.g., by a user) to retain the accessory 135. For example,in some embodiments, the power tool 100 is a chop saw that receives atan arbor a blade or grinder from a plurality of different types ofblades and grinders.

In block 310, an accessory-type detector 145, coupled to or integratedwithin the electric tool 100, detects a characteristic of the accessory135. As noted above, in some embodiments, the accessory-type detector145 is connected to the electric tool 100 such that the accessory-typedetector 145 detects the accessory characteristic of the accessory 135.For example, the accessory-type detector 145 may be mounted on thehousing 115 or the blade guard 120. The motor controller 220 receivesdata from the accessory-type detector 145 that indicates the accessorycharacteristic. For example, in some embodiments, the accessorycharacteristic is at least one selected from the group of a materialtype (e.g., metal versus non-metal), a blade type (e.g., chop saw bladeversus grinder), a texture, shape, or size of the accessory or a portionof the accessory, and an identifying mark (e.g., that identifies one ormore of the type of accessory, model number, material type, blade type,texture type, shape, or size). For example, the accessory-type detector145 may be an inductive sensor that outputs a digital signal indicatingthe presence or absence of metal (e.g., digital logic signal of “0”indicates metal, digital logic signal of “1” indicates non-metal). Inanother embodiment, the accessory-type detector 145 is a bar code readerthat outputs a first value when no bar code is read or an invalid barcode is read, and outputs another value indicative of a read bar codevalue when a bar code is read. In another embodiment, the accessory-typedetector 145 is an optical sensor, Hall sensor, inductive sensor,capacitive sensor, or the like, that outputs an analog signal (e.g.,between 0-3.3 volts or 0-5 volts) indicative of the sensedcharacteristic. For example, the range of potential analog signal valuescorresponds to the levels of the characteristic that can be sensed bythe sensor. For example, when the accessory-type detector 145 is a Hallsensor, the sensor outputs 0 volts when no or very low magnetic field issensed, and outputs 2.5 volts when a medium strength magnetic field(e.g., from a magnet on the accessory 135) is sensed, and outputs 5volts when a strong magnetic field is sensed. Various other sensor typesand configurations are contemplated in different embodiments.

In block 315, the motor controller determines an operationalcharacteristic for the accessory 135 based on the accessorycharacteristic. The memory of the motor controller 220 may associatevarious accessory characteristics to corresponding accessory operationalcharacteristics for controlling the motor 210 and the accessory 135.

For example, in some embodiments, the memory of the motor controller 220includes a data table mapping accessory characteristics to operationalcharacteristics, where the accessory characteristics serve as an indexinto the table and the operational characteristics are correspondingoutputs of the table. For example, in some embodiments, the memory mapsan abrasive blade type (an accessory characteristic of some chop sawblades) to a first motor speed (an example operational characteristic),and a metal blade (an accessory characteristic of some other chop sawblades) to a second motor speed (another example operationalcharacteristic), where the first motor speed is faster than the secondmotor speed. However, the disclosure is not limited to this or otherspecific mappings between accessory characteristics to correspondingoperational characteristics. The data table may be generated throughtesting and stored in the memory at the time of manufacture and/or maybe updated. Additionally, the data table may be particular to the typeof electronic tool 100. In other words, as an example, the data tablefor a chop saw may be different than the data table for a drill-driver.

In block 320, when the power tool trigger 140 is actuated by a user, themotor controller controls operation of the motor 210 to drive the outputdriver 220 and the accessory 135 according to the operationalcharacteristic determined based on the accessory characteristic. Forexample, in some embodiments, the operational characteristic sets apulse width modulated (PWM) duty ratio for driving the FETs 205, whichthereby sets the speed of the motor 210. For example, when cycling powerto the FETs 205 to drive the motor, the driving signal selectivelyprovided by the motor controller 220 to each FET 205 is provided withthe determined PWM duty ratio. In other embodiments, the operationalcharacteristic is a current driving value, a current threshold, an inputinto a proportional-integral-derivative (PID) controller setting atarget motor speed or other operational characteristics of theelectronic tool 100.

In some embodiments, in block 310, in addition to or instead of theaccessory-type detector 145 detecting a characteristic of the accessory135, the accessory-type detector 145 detects, and provides an indicationto the motor controller 220, of whether an accessory is coupled to orproperly coupled to the output driver 212. In response to receiving anindication from the accessory-type detector 145 that an accessory is notcoupled or not properly coupled to the output driver 212, the motorcontroller 220 disables activation of the motor based on theaccessory-type detector 145 detecting that the accessory is not receivedby the output driver 212. For example, the motor controller 220 maycontinue to loop on block 310 until an accessory is detected as coupledor properly coupled to the output driver 212, rather than proceeding toblock 315. However, in response to receiving an indication from theaccessory-type detector 145 that an accessory is coupled or properlycoupled to the output driver 212, the motor controller enablesactivation of the motor based on the accessory-type detector detectingthat an accessory is received by the output driver. For example, themotor controller 220 may proceed to block 315 upon detecting that anaccessory is coupled or properly coupled to the output driver 212. Inone embodiment, the motor controller 220 determines that an accessory iscoupled when the accessory-type detector 145 outputs valid data. Forexample, when the accessory-type detector 145 is a Hall sensor and theaccessories are expected to have a magnet to be sensed by the Hallsensor, an indication of 0 volts (or less than some threshold value)from the Hall sensor may indicate the absence of the accessory 135,while an indication of 5 volts (or above some threshold value) becausethe magnetic field of the magnet of the accessory 135 impinges thesensor indicates the presence of the accessory 135.

As noted above, although the exemplary electric tool 100 is shown as achop saw, the electric tool 100 may be any electric tool (or power tool)that drives an output driver. FIG. 4 illustrates an example of a pipethreader electric tool that has a pipe material-type detector. Referringto FIG. 4, a pipe threader 410 has a housing 414 including a gearcase416, a drive assembly 418 including a motor and a transmission (notshown), and a die holder 430 for selectively receiving a die 434 withteeth for cutting threads on a pipe (not shown) and defining arotational axis 432. The motor is powered by a battery 438 that isselectively coupled to the housing 414. The housing 414 further includesan operating handle 442 and a support handle 446. The pipe threader 410includes a trigger 450 on the operating handle 442 for activating themotor, and a speed shift knob 454 allowing an operator to switch the dieholder 430 (and thus the die 434) between a high rotational speed and alow rotational speed. The pipe threader 410 has a material-type detector412 that is mounted on the housing 414. The pipe threader 410 alsoincludes a motor controller, such as the motor controller 220, that isalso communicatively coupled to the material-type detector 412 and thepipe threader motor (the motor 210), as illustrated in FIG. 2. In someembodiments of the pipe threader, the motor controller 220 is configuredto read sensor data from the material-type detector 412 and controloperational characteristics of the pipe threader 410 such as speed,torque, current draw, or other motor or tool performance characteristic.

The material-type detector 412 may be mounted on the housing 414 oranother structure of the pipe threader 410 such that the material-typedetector 412 is able to detect the type of material of the pipe. In someembodiments, the material-type detector 412 has a first sensing side anda second mounting side opposite the first sensing side. The mountingside may be secured to the housing 414 (e.g., via fasteners, adhesive,welding, and the like), while the sensing side includes a sensor with asensing face directed toward a surface of a pipe that is received by thepipe threader 410. The material-type detector 412 is configured todetect one or more characteristics of the pipe. In some embodiments, thematerial-type detector 412 includes an inductive sensor that detects andprovides an indication of whether the pipe is metal or non-metal. Insome embodiments, the material-type detector 412 includes an opticalsensor that detects and provides an indication of a characteristic suchas the type, size, shape, texture, or material of the received pipe.Other suitable types of sensors may be used as the material-typedetector 412, for example, radio frequency identification (RFID), sound,light, tactile or heat sensors. Moreover, in some embodiments, thereceived pipe may comprise an identifying mark or a tag that may besensed or read by the material-type detector 412, and may indicate whichtype of pipe is received by the pipe threader 410. The mark or tag mayinclude, among other things, one or more of an RF or RFID emitter, anoptically detectable feature such as a type of bar code, a color, alight emitter, and an acoustically detectable feature or sound emitter.

The material-type detector 412 is configured to sense the type ofmaterial from which the pipe is made (e.g., when the pipe is received bythe pipe threader for threading). Based on the type of material sensedby the material-type detector 412, the motor controller 220 isconfigured to vary operational characteristics such as speed, torque,pressure, or other motor or tool performance characteristic to improvethe threading of the pipe being threaded. For example, an operator mayarrange the die 434 on a pipe to be threaded and the material-typedetector 412 may determine the type of material of the pipe. Theoperator may press against a non-rotating portion of the die 434 in thedirection of the rotational axis 432. The operator then presses trigger450 to activate the motor. As a result, the transmission transmitstorque from the motor to the die holder 430 such that the die holder 430rotates while holding the die 434, causing the die 434 to rotate andmove along the pipe to cut threads on the pipe. Based on the type ofmaterial sensed by the material-type detector 412, the motor controller220 is configured to vary operational characteristics of the pipethreader 410 such as the speed, torque, pressure, and/or other motor ortool performance characteristic to improve the threading of the pipe.For example, the motor controller 220 may increase the speed or torqueof the motor 126 by increasing the duty cycle of a PWM signal that formsthe control signals provided to the FETs 205, resulting in increasedcurrent flowing to the stator coils of the motor 210. Similarly, themotor controller 220 may decrease the speed or torque of the motor 126by reducing the duty cycle. The particular operational characteristicfor a particular detected material may specified in a lookup tablestored in the memory of the motor controller 220. For example, the motorcontroller 220 may apply the identified material type to the lookuptable as an input/index, and the output of the lookup table indicatesthe operational characteristic.

In another embodiment, the electronic tool 100 may be a saw (e.g., thechop saw as shown in FIG. 1, reciprocating saw, or circular saw) thatincludes a material-type detector 412. The material-type detector 412may be also be mounted on a housing, blade guard, or any other structureof the saw such that the material-type detector 412 is able to detectthe type of material of the work piece. For example, in FIG. 1, thematerial-type detector 412 is shown integrated into the base of the chopsaw. The material-type detector 412 is configured to sense the type ofmaterial that is being cut (e.g., metal, wood, a density of wood, etc.).For example, the material-type detector 412 may be a ferromagneticsensor or a density sensor, etc. Using similar techniques as describedabove, based on the type of material sensed by the material-type sensor412, the motor controller 220 is configured to vary an operationalcharacteristic such as speed, torque, current draw, or other motor ortool performance characteristic to improve cutting performance of thework piece based on the type of material being cut. In some embodiments,with reference FIG. 3, the motor controller 220 determines theoperational characteristic in block 315 based on both the identifiedaccessory type of the accessory 135 (detected by the accessory typedetector 145) and the identified material type of the workpiece(detected by the material-type detector 415). For example, a lookuptable stored in the memory of the motor controller 220 may map accessorytypes and workpiece material types to an operational characteristic.

Thus, the disclosure provides, among other things, automatic control ofpower tools based on detection of power tool accessory type or accessorypresence by an accessory-type detector. Various features and advantagesof the disclosure are set forth in the following claims.

We claim:
 1. A method for controlling operation of a power tool, themethod comprising: receiving an accessory by an output driver of thepower tool, the output driver coupled to a motor of the power tool,wherein the accessory is driven by the motor; detecting, by a motorcontroller of the power tool, a characteristic of the accessory using anaccessory-type detector that is coupled to the motor controller;determining, by the motor controller, an operational characteristic forthe accessory based on the characteristic of the accessory detected bythe motor controller; and automatically controlling, by the motorcontroller, operation of the motor that drives the accessory accordingto the operational characteristic when an operation trigger of the powertool is activated.
 2. The method of claim 1, wherein the power tool is achop saw and the accessory-type detector is mounted on a blade guard ofthe chop saw.
 3. The method of claim 1, wherein the accessory is a sawblade and the accessory characteristic comprises a material of which thesaw blade is made.
 4. The method of claim 1, wherein the operationalcharacteristic comprises a speed for rotating the motor that drives theoutput driver and the accessory.
 5. The method of claim 1, wherein thecharacteristic of the accessory comprises a physical characteristic ofthe accessory or a modification made to the accessory.
 6. The method ofclaim 1 further comprising: disabling, by the motor controller,activation of the motor when the accessory-type detector detects thatthe accessory is not received by the output driver.
 7. The method ofclaim 1 further comprising: enabling activation of the motor when theaccessory-type detector detects that the accessory is received by theoutput driver.
 8. A power tool comprising: an output driver forreceiving an accessory; an accessory-type detector; a motor coupled tothe output driver for driving the accessory; an operation trigger foractivating the motor; and a motor controller comprising an electronicprocessor coupled to the accessory-type detector, the motor, theoperation trigger, and a memory, wherein the memory stores instructionsthat when executed by the electronic processor configure the motorcontroller to: detect, from output of the accessory-type detector, acharacteristic of the accessory, determine an operational characteristicfor the accessory based on the characteristic of the accessory detectedby the motor controller, and control operation of the motor to drive theaccessory according to the operational characteristic when the operationtrigger is activated.
 9. The power tool of claim 8, wherein the powertool is a saw and the accessory-type detector is mounted on a bladeguard of the saw.
 10. The power tool of claim 8, wherein the power toolis a saw and the accessory-type detector is mounted on a housing of thesaw.
 11. The power tool of claim 8, wherein the accessory is a saw bladeand the accessory characteristic comprises a material of which the sawblade is made.
 12. The power tool of claim 8, wherein the operationalcharacteristic comprises a speed for rotating the motor that drives theoutput driver and the accessory.
 13. The power tool of claim 8, whereinthe characteristic of the accessory comprises a physical characteristicof the accessory or a modification made to the accessory.
 14. The powertool of claim 8, wherein the motor controller is further configured to:disable activation of the motor when the accessory-type detector detectsthat the accessory is not received by the output driver; and enableactivation of the motor when the accessory-type detector detects thatthe accessory is received by the output driver.
 15. The power tool ofclaim 8, further comprising: a material-type detector, wherein theaccessory is a saw blade, wherein the memory stores further instructionsthat, when executed by the electronic processor configure the motorcontroller to detect, from output of the material-type detector, acharacteristic of a workpiece for cutting by the saw blade, and whereindetermining the operational characteristic for the accessory is furtherbased on the detected characteristic of the workpiece.
 16. A chop sawcomprising: an arbor configured to receive an accessory in the form of asaw blade; a base configured to receive a workpiece; a motor housing; amotor, supported by the motor housing, that is coupled to the arbor fordriving the arbor; a hinge pivotably coupling the base to the motorhousing; an operation trigger for activating the motor; and anaccessory-type detector; a motor controller comprising an electronicprocessor coupled to the accessory-type detector, the motor, theoperation trigger, and a memory, wherein the memory stores instructionsthat when executed by the electronic processor configure the motorcontroller to: detect, from output of the accessory-type detector, acharacteristic of the saw blade, determine an operational characteristicfor the saw blade based on the characteristic of the saw blade detectedby the motor controller; and control operation of the motor to drive thesaw blade according to the operational characteristic when the operationtrigger is activated.
 17. The chop saw of claim 16, wherein theaccessory-type detector is mounted on a blade guard of the saw.
 18. Thechop saw of claim 16, the accessory characteristic comprises at leastone selected from the group of a material of which the saw blade ismade, a physical characteristic of the saw blade, and a modificationmade to the saw blade.
 19. The chop saw of claim 16, wherein theoperational characteristic comprises a speed for rotating the motor thatdrives the arbor and the saw blade.
 20. The chop saw of claim 16,further comprising: disabling, by the motor controller, activation ofthe motor when the accessory-type detector detects that the saw blade isnot received by the output driver; and enabling activation of the motorwhen the accessory-type detector detects that the saw blade is receivedby the output driver.
 21. A pipe threader comprising: a die with teethfor cutting threads on a pipe; a material-type detector; a motor coupledto the die, the motor for driving rotation of the die; an operationtrigger for activating the motor; and a motor controller comprising anelectronic processor coupled to the material-type detector, the motor,the operation trigger, and a memory, wherein the memory storesinstructions that when executed by the electronic processor configurethe motor controller to: detect, from output of the material-typedetector, a characteristic of a pipe received by the die, determine anoperational characteristic for threading the pipe based on the detectedcharacteristic of a pipe received by the die, and control operation ofthe motor to drive rotation of the die according to the operationalcharacteristic when the operation trigger is activated.